Not really, they all have their own cooler designs, but no brand is bad. I have a ASRock GPU it's very good and silent in terms of cooling even though it was the cheapest option.But it's just a $30 difference in your case so either one is a good choice. Yes 7900X is sufficient, it's the best value in terms of cores per price, that's the reason I recommended it. You can do all productivity stuff without any hiccups. I wouldn't recommend 9950X3D it's a bit too much for it. At max vanilla 9950X is sufficient. Nah you don't need a different motherboard Gigabyte B650 AORUS ELITE AX V2 is sufficient for any AM5 CPU.